Tom Lane wrote:
> "ADBAAMD" <adba.amdocs@bell.ca> writes:
>
>> Tom Lane wrote:
>>
>>> This behavior is a bit of a hack, which we'll likely reconsider in
>>> future releases, but it does have some redeeming social value too.
>
>> Perhaps it would be cleaner to have somehing like Oracle's hints?
>
> Possibly. Want to enlighten those of us who've never used Oracle about
> how that works?
You can read (almost) all about it at
http://technet.oracle.com/doc/server.804/a58246/toc.htm, more to the
point http://technet.oracle.com/doc/server.804/a58246/optimiz.htm#2250.
For example:
SELECT /*+ STAR */
doc_id
FROM
written_by AS wb
JOIN
author_keyword AS kw
ON
kw.author_id = wb.author_id
WHERE
kw.keyword = 'foo'
;
There is also a /*+ ORDERED */ hint, but I dislike it as it also requires
query rewriting. Keep in mind I have an opinion against having to
rewrite queries for performance reasons, thinking this should be done at
the optimizer or preferably at the physical level or the
logical-to-physical mapping.
Also it does not seems to me very nice to have queries changing behaviour
from version to version and then back again.
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